Littérature scientifique sur le sujet « Anthracene-9-methanol »

The molecular structures of di(9-anthryl)methanol (1) and di(9-anthryl) ketone (2) have been established by X-ray diffraction. The asymmetric unit of di(anthryl)methanol consists of two molecules in which the dihedral angle between the anthracene moieties is 81.4 and 86.3 respectively; steric interaction between the anthracene moieties results in them subtending angles of 115.0(7) and 115.8(8)� at the central carbon atom, and with unsymmetrical exocyclic angles at their point of attachment. In di(9-anthryl) ketone the planes of the anthracene systems are twisted out of the plane of the carbonyl group by 48.8 and 52.2� respectively, so that the dihedral angle between the two aromatic ring systems is 87.3�. The structures of di(anthryl)methanol and di(anthryl) ketone are discussed with respect to their different modes of photochemical isomerization by intramolecular cycloaddition.

Radical oxidation and addition reactions of anthracene (1), 9-methylanthracene (2) and 9-phenylanthracene (3) were investigated with dimethyl malonate (4) in the presence of ceric ammonium nitrate (CAN) and manganese(III) acetate (Mn(OAc)3). Although mostly anthraquinone derivatives and bianthrone were obtained with CAN, substituted 9,10-dihydroanthracene and 9,10-substituted anthracene derivatives were obtained with Mn(OAc)3. Dimethylmalonyl addition products (5a, 33 % and 5b, 42 %) were obtained in higher yield than quinones (5d, 8 % and 5e, 3 %) using Mn(OAc)3 as oxidant. 9a (96 %) and 9b (84 %) were synthesized in high yield and substitution products (7a, 44 % and 8b, 56 %) were obtained in higher yields than quinones (5d and 5e) using CAN as oxidant. The reactions were carried out in non-acidic medium (dichloromethane and methanol). Based on the structures of the isolated products a mechanism for these transformations was proposed.

A novel on-line micro pressurized liquid extraction (μPLE) method is introduced, which directly interfaces miniaturized solid sample preparation with HPLC for fast analysis. The technique employs rapid heating to remove analytes from 5–10 mg samples in typically 20–40 s using only about 300 μL of solvent. The resulting extract is then internally transferred to an HPLC injector for chromatographic analysis. Results show that good analyte recoveries can be achieved, similar to conventional PLE and off-line μPLE approaches, without manual sample handling. For example, 103% ± 3% (n = 4) of the acetylsalicylic acid present in pharmaceutical tablets was extracted into methanol after 20 s at 180 °C. Further, 105% ± 9% (n = 4) of the caffeine present in a green tea sample was extracted into methanol after 40 s at 275 °C. Typical time to analysis was about 95 s total for most samples, and solvents could also be easily alternated during trials to increase extract selectivity. The on-line μPLE system was applied to the extraction of model PAHs from a biochar matrix and was found to extract 97% ± 5% (n = 4) of anthracene present in the sample after a 30 s static and 60 s dynamic extraction at 220 °C. This yield is much better than results obtained by previous approaches and is attributed to the small size, high temperature, low thermal mass, and dynamic flow of the system. Findings indicate that the on-line μPLE system can greatly assist in such extractions and provide a useful method for rapidly preparing solid samples for analysis using little solvent.

Rhazya stricta is a medicinal plant that is widely used in Saudi folklore medicine for treatment of various diseases. R. stricta fruit powder was sequentially extracted with n-hexane, chloroform, ethyl acetate, and methanol using a Soxhlet extractor. The cytotoxic effects of these fractions on human breast cancer cells (MDA-MB-231 and MCF-7) and non-tumorigenic control cells (MCF-10A) were evaluated via cell viability measurements, microscopy, gene expression, and migration assays. Moreover, the effect of the most promising extract on 7,12-dimethyl-benz[a]anthracene (DMBA)-induced breast cancer was investigated in rats. The promising extract was also subjected to gas chromatography–mass spectrometry. Fruit extracts of R. stricta were significantly cytotoxic toward all tested cell lines, as demonstrated by MTT and LDH assays. Treatment of MDA-MB-231 cells with fruit ethyl acetate fraction (RSF EtOAc) increased expression 11of P53, Bax and activation of caspase 3/7. A cell migration scratch assay demonstrated that extracts at non-cytotoxic concentrations exerted a potent anti-migration activity against the highly invasive MDA-MB-231 cell line. Moreover, RT-PCR results showed that RSF EtOAc significantly downregulated MMP-2 and MMP-9 expression, which play an important role in breast cancer metastasis. Histological studies of breast tissue in experimental animals showed a slight improvement in tissue treated with fruit ethyl acetate extract. GC-MS chromatogram showed thirteen peaks with major constituents were camphor, trichosenic acid and guanidine. Our current study demonstrates that fruit extracts of R. stricta are cytotoxic toward breast cancer cell lines through apoptotic mechanisms.

TMEM16B, also known as anoctamin 2 has been recently identified as a calcium-activated chloride channel. It is expressed at the synaptic terminals of photoreceptors, in hippocampal cells, in the cilia of olfactory sensory neurons and in the microvilli of vomeronasal sensory neurons. TMEM16B, as its most known cousin TMEM16A, is activated both by calcium and voltage. When this thesis was started there was no available data correlating the gating function and protein structure in TMEM16B. In our first manuscript, we show a coupling between calcium and voltage in TMEM16B activation. Primary sequence analysis did not show any canonical calcium binding sites nor S4-like dedicated voltage sensors. However, the first intracellular loop contains several negatively charged amino acids. We performed site directed mutagenesis at 367E, and 386EEEEE390 in the first intracellular loop and investigated their role in calcium or voltage dependence of TMEM16B. Either neutralizing or deleting these acidic residues strongly shifted the conductance-voltage relation towards more positive voltages without a significant effect on the apparent calcium sensitivity. Our findings indicate involvement of glutamic acids from the first intracellular loop in voltage dependent activation of TMEM16B, and provides an initial structure-function study for this channel. In our second manuscript, we focused on understanding the effect of permeant anions on TMEM16B activation. Our results show TMEM16B is poorly selective among anions and has a permeability sequence of SCN- > I- > NO3- > Br- > Cl- > F- > gluconate. The channel kinetics also shows dependence on the permeant anion, with more permeable anions, such as SCN-, causing a much slower activation and deactivation kinetics than Cl-. Moreover, SCN- facilitated the channel activation by lowering the half-maximal concentration of calcium required for opening the channel and shifting the conductance-voltage relation towards less positive voltages. From this work we report the existence of a crosstalk between calcium, voltage and permeant anion in TMEM16B activation. Furthermore, we looked for a compound that could modulate the function of TMEM16B. We found that anthracene-9-carboyxlic acid, one of the traditional calcium-activated chloride channel blockers is very interesting since it had multiple effects on TMEM16B. In our third manuscript we report the block by A9C as voltage and concentration dependent, with maximal inhibition at positive voltages. Surprisingly, A9C also potentiated the current at intermediate concentrations and negative voltages. However, anthracene-9-methanol (A9M), a non-charged analog of A9C, completely abolished the voltage dependent inhibition and the potentiation effect seen with A9C. Both A9C and A9M had much slower current kinetics. This indicates the requirement of negative charge of A9C for its voltage dependent block of outward currents and potentiation of inward currents. In summary, the studies included in this thesis reveal a complex coupling between calcium, voltage, and permeant anion in TMEM16B activation. The identification of a compound have contrasting effects on the channel activation, provides a new tool for future structure-function studies on this channel.